mpd/src/decoder/plugins/HybridDsdDecoderPlugin.cxx
2018-02-13 09:53:05 +01:00

284 lines
6.9 KiB
C++

/*
* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "HybridDsdDecoderPlugin.hxx"
#include "../DecoderAPI.hxx"
#include "input/InputStream.hxx"
#include "system/ByteOrder.hxx"
#include "util/Domain.hxx"
#include "util/WritableBuffer.hxx"
#include "util/StaticFifoBuffer.hxx"
#include "Log.hxx"
#include <string.h>
static constexpr Domain hybrid_dsd_domain("hybrid_dsd");
namespace {
static bool
InitHybridDsdDecoder(const ConfigBlock &block)
{
/* this plugin is disabled by default because for people
without a DSD DAC, the PCM (=ALAC) part of the file is
better */
if (block.GetBlockParam("enabled") == nullptr) {
LogInfo(hybrid_dsd_domain,
"The Hybrid DSD decoder is disabled because it was not explicitly enabled");
return false;
}
return true;
}
/**
* This exception gets thrown by FindHybridDsdData() to indicate a
* file format error.
*/
struct UnsupportedFile {};
struct Mp4ChunkHeader {
uint32_t size;
char type[4];
};
void
ReadFull(DecoderClient &client, InputStream &input,
WritableBuffer<uint8_t> dest)
{
while (!dest.empty()) {
size_t nbytes = client.Read(input, dest.data, dest.size);
if (nbytes == 0)
throw UnsupportedFile();
dest.skip_front(nbytes);
}
}
void
ReadFull(DecoderClient &client, InputStream &input, WritableBuffer<void> dest)
{
ReadFull(client, input, WritableBuffer<uint8_t>::FromVoid(dest));
}
template<typename T>
T
ReadFullT(DecoderClient &client, InputStream &input)
{
T dest;
ReadFull(client, input, WritableBuffer<void>(&dest, sizeof(dest)));
return dest;
}
Mp4ChunkHeader
ReadHeader(DecoderClient &client, InputStream &input)
{
return ReadFullT<Mp4ChunkHeader>(client, input);
}
uint32_t
ReadBE32(DecoderClient &client, InputStream &input)
{
return FromBE32(ReadFullT<uint32_t>(client, input));
}
} /* anonymous namespace */
static std::pair<AudioFormat, offset_type>
FindHybridDsdData(DecoderClient &client, InputStream &input)
{
auto audio_format = AudioFormat::Undefined();
bool found_version = false;
while (true) {
auto header = ReadHeader(client, input);
const size_t header_size = FromBE32(header.size);
if (header_size < sizeof(header))
throw UnsupportedFile();
size_t remaining = header_size - sizeof(header);
if (memcmp(header.type, "bphv", 4) == 0) {
/* version; this plugin knows only version
1 */
if (remaining != 4 || ReadBE32(client, input) != 1)
throw UnsupportedFile();
remaining -= 4;
found_version = true;
} else if (memcmp(header.type, "bphc", 4) == 0) {
/* channel count */
if (remaining != 4)
throw UnsupportedFile();
auto channels = ReadBE32(client, input);
remaining -= 4;
if (!audio_valid_channel_count(channels))
throw UnsupportedFile();
audio_format.channels = channels;
} else if (memcmp(header.type, "bphr", 4) == 0) {
/* (bit) sample rate */
if (remaining != 4)
throw UnsupportedFile();
auto sample_rate = ReadBE32(client, input) / 8;
remaining -= 4;
if (!audio_valid_sample_rate(sample_rate))
throw UnsupportedFile();
audio_format.sample_rate = sample_rate;
} else if (memcmp(header.type, "bphf", 4) == 0) {
/* format: 0 = plain DSD; 1 = DST compressed
(only plain DSD is understood by this
plugin) */
if (remaining != 4 || ReadBE32(client, input) != 0)
throw UnsupportedFile();
remaining -= 4;
audio_format.format = SampleFormat::DSD;
} else if (memcmp(header.type, "bphd", 4) == 0) {
/* the actual DSD data */
if (!found_version || !audio_format.IsValid())
throw UnsupportedFile();
return std::make_pair(audio_format, remaining);
}
/* skip this chunk payload */
input.LockSkip(remaining);
}
}
static void
HybridDsdDecode(DecoderClient &client, InputStream &input)
{
if (!input.CheapSeeking())
/* probe only if seeking is cheap, i.e. not for HTTP
streams */
return;
uint64_t total_frames;
size_t frame_size;
unsigned kbit_rate;
try {
auto result = FindHybridDsdData(client, input);
auto duration = SignedSongTime::FromS(result.second / result.first.GetTimeToSize());
client.Ready(result.first, true, duration);
frame_size = result.first.GetFrameSize();
kbit_rate = frame_size * result.first.sample_rate /
(1024u / 8u);
total_frames = result.second / frame_size;
} catch (UnsupportedFile) {
/* not a Hybrid-DSD file; let the next decoder plugin
(e.g. FFmpeg) handle it */
return;
}
const offset_type start_offset = input.GetOffset();
offset_type remaining_bytes = total_frames * frame_size;
StaticFifoBuffer<uint8_t, 16384> buffer;
auto cmd = client.GetCommand();
while (remaining_bytes > 0) {
uint64_t seek_frame;
switch (cmd) {
case DecoderCommand::NONE:
case DecoderCommand::START:
break;
case DecoderCommand::STOP:
return;
case DecoderCommand::SEEK:
seek_frame = client.GetSeekFrame();
if (seek_frame >= total_frames) {
/* seeking past the end */
client.CommandFinished();
return;
}
try {
input.LockSeek(start_offset + seek_frame * frame_size);
remaining_bytes = (total_frames - seek_frame) * frame_size;
buffer.Clear();
client.CommandFinished();
} catch (...) {
LogError(std::current_exception());
client.SeekError();
}
cmd = DecoderCommand::NONE;
break;
}
/* fill the buffer */
auto w = buffer.Write();
if (!w.empty()) {
if (remaining_bytes < (1<<30ull) &&
w.size > size_t(remaining_bytes))
w.size = remaining_bytes;
const size_t nbytes = client.Read(input,
w.data, w.size);
if (nbytes == 0)
return;
remaining_bytes -= nbytes;
buffer.Append(nbytes);
}
/* submit the buffer to our client */
auto r = buffer.Read();
auto n_frames = r.size / frame_size;
if (n_frames > 0) {
cmd = client.SubmitData(input, r.data,
n_frames * frame_size,
kbit_rate);
buffer.Consume(n_frames * frame_size);
}
}
}
static const char *const hybrid_dsd_suffixes[] = {
"m4a",
nullptr
};
const struct DecoderPlugin hybrid_dsd_decoder_plugin = {
"hybrid_dsd",
InitHybridDsdDecoder,
nullptr,
HybridDsdDecode,
nullptr,
nullptr,
/* no scan method here; the FFmpeg plugin will do that for us,
and we only do the decoding */
nullptr,
nullptr,
hybrid_dsd_suffixes,
nullptr,
};